(1) Field of the Invention
The present invention relates generally to tap-resistant wiring and, more particularly, to a tap-resistant conduit especially adaptable for automotive anti-theft security systems. Such wiring may also be used to enhance security of communications networks.
(2) Description of the Prior Art
Security is becoming increasingly important whether it is to prevent a car theft or the interception of confidential information from a "secure" telephone or data line.
Automobile security systems have continued to improve over the years but, in most cases, once the thief is in the car he will be able to start it by bypassing the ignition switch and "hot wiring" the car. More sophisticated systems using "smart" keys are more difficult to bypass but also may not allow the real owner to operate the car by due to a false negative if the system fails to identify the key properly.
With regard to communications, encryption technology also has improved but can possibly be broken and, sometimes, may result in problems between the parties trying to communicate. In addition, the cost may be prohibitive when many lines are required.
U.S. Pat. No. 4,122,436, issued to Gmeiner et al., discloses an installation for the protection of a line, such as a telephone line. The line is surrounded at least within its area potentially endangered by external influences by a coaxially arranged tubular member with the annular space disposed between the line and the tubular member filled with a control media which will trigger a warning indication in case of an unusual pressure change caused, for example, by mechanical damage to the outer tubular member. In the preferred embodiment, this invention is directed towards detecting damage to a vacuum-operated headlight adjustment system and alerting the driver.
Therefore, while Gmeiner et al. discloses a gas-filled conduit surrounding a wire to detect a failure, there is no suggestion of using the pressure of the gas to maintain the connection of the wire in its normal operating state and, when there is a break in the conduit, disengaging the wire contact to disable the circuit.
Thus, there remains a need for a new and improved tap-resistant conduit which does not normally require special circuity or encryption while, at the same time, is simple to install and will reliably prevent the operation of the circuit if an attempt to tap or hot wire the circuit is made.